In recent years, with electronic components having a higher performance and control substrates having a higher density, a remarkably-increased amount of heat has been emitted from control substrates. Furthermore, more electronic components for example have been provided to have a smaller size, a higher integration and a higher amount of information to be processed. Thus, an efficient cooling is required in the vicinity of a heat-generating unit. Thus, a cooling system has been suggested to cool a rack-type server using a water-cooling jacket (see for example Patent Publication 1).
The following section will describe a conventional cooling system to cool a rack-type server. A cabinet constituting an electronic device includes a plurality of electronic devices to form a plurality of stages. One electronic device accommodates a Central Processing Unit (CPU) as a semiconductor device from which heat is generated. This CPU is cooled by liquid circulated by the first pump in the first cooling system.
This first cooling system is thermally connected to the second cooling system having the second pump attached to the rear side of the cabinet. This second pump is connected to a piping. This piping is inserted to the interior of each electronic device of each stage. The piping raised from the second pump to be parallel to the cabinet is abutted on an inner wall face of the cabinet.
The piping inserted to the interior of each electronic device is attached with two heat-receiving units among which one heat-receiving unit is thermally connected to the heat-receiving jacket of the first cooling system and the other heat-receiving unit is thermally connected to a heat exchanger. The cooling liquid discharged from the second pump is circulated through the respective electronic devices of the respective stages and is subsequently collected by the second pump.
By the above configuration, the heat generated from the CPUs of the respective electronic devices is transmitted via the piping to the cabinet. Then, the heat is naturally released in the entire cabinet or is forcedly discharged by a cooling fan provided in the cabinet.
In the case of the conventional cooling system as described above, a disadvantage was caused in that the first cooling system cooled by water requires each electronic device to have the first pump for water circulation, thus causing increased power consumption. Furthermore, the heat from the heat-generating body (CPU) is finally discharged to the exterior of the cabinet, thus causing a disadvantage in an increased temperature in a place whether the cabinet is provided.